People nowadays substantially rely on technology. Advance of the technology has enriched the functions of portable electronic products. Their profiles also are designed with enhanced appeal. Some portable electronic products are quite expensive. Hence many users use a protective film or protective cover to protect the surface of the portable electronic products from abrasion. Some people also use a protective casing to hold the portable electronic device to prevent its appearance from wearing and also avoid impact from external forces via the hard shell or thicker soft shell to prohibit accidental damage.
Some portable electronic products, such as iPad, iPhone or other smart phones have multiple buttons on the circumference thereof. The protective casing usually is formed at a greater thickness. In the event that the designed dimension does not fit exactly, the buttons often are blocked by the protective casing that makes pressing difficult. More important, the portable electronic products usually have a speaker located on the circumference. To avoid the sound output from the speaker from being blocked by the protective casing, the protective casing must have an opening mating the speaker to prevent blocking of the sound. The opening can only avoid sound from blocking, but cannot enhance or improve the sound quality.